Effect of physostigmine on memory consolidation and retrieval processes in intact and nucleus basalis-lesioned rats.

The efficacy of physostigmine on memory enhancement in rats trained on a passive avoidance task was investigated. In experiment 1, the effect of posttraining injections of physostigmine (0.03 mg/kg) in subjects tested at either short (1.25 h or 72 h) or long (3 weeks or 5 weeks) retention intervals was explored. Results indicated drug-induced enhancement of memory at only the two short intervals. Experiment 2 examined the mnemonic consequences of pretest administration of physostigmine. Administration of physostigmine (0.015 mg/kg and 0.03 mg/kg) shortly prior to testing led to a significant potentiation of memory retrieval. The aim of experiment 3 was to determine whether or not an intact cholinergic system is necessary for pretest physostigmine to enhance memory retrieval. Results from this experiment indicated that physostigmine (0.03 mg/kg) was effective in enhancing memory in rats prepared with ibotenic acid-induced lesions of the nucleus basalis of Meynert. Together, these data provide further empirical support for the importance of the cholinergic system in memory processes.